This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this project is to test two candidate vaccines for protection of macaques against Simian Type D Retrovirus (SRV) serotype 2. If successful, this may be helpful in preventing a common spontaneous retrovirus induced immunosuppressive disease in macaques. Infection with SRV-2 is prevalent in wild and has been common in captive macaques and is capable of causing an AIDS like disease in simians. Rapidly spread through body fluids (salvia or blood), SRV-2 can cause an endemic infection of wild and captive macaques colonies. There are currently 8 animals on this study. In phase 1, two animals will be inoculated IV with SRV obtained from in house sources at the Tulane Primate Center. Blood samples, lymph node and intestinal biopsies and saliva were negative for SRV. Another stock of SRV had been obtained from the University of California Davis was used to re-inoculate the 2 monkeys. All post-inoculation SRV infection and pathogenesis were positive for infection by PCR. In phase 2, all animals will be used in vaccine study VSV boosting vaccine strategy. Four rhesus macaques were immunized with VSV-SRV env/gag hybrid viruses. Two additional vaccine negative monkeys and 4 immunized monkeys were challenged intravenously with SRV-2. All control monkeys were positive by PCR for viremia and all 4 immunized monkeys were completely protected. Therefore, VSV-immunization was capable of inducing sterilizing immunity against SRV-2.